Two years back
I have moved to Nefteyugansk (Russia, Siberia) where I could not receive the sanction
to installation for a full-sized
HF- antenna on the roof
of my house. , So I began to do experimenters with short indoors
antennas. Most success design of my indoor antenna is a design
similar to Fig. 59, given in Reference
1.
I have used
an inch OD plastic pipe to the form of the antennal. The pipe
was bent in a hoop near1 meter diameter. Antenna has 580 turns
(near 61 meters of length) of multicore isolated wire of 3 mm
diameter with thickness of isolation of 1 mm. So, the spacing
between turns is 2 mm. Antenna has SWR 1:1 to 50-Ohm coaxial cable
to 14.100, bandwidth to SWR 1:1.5 is 300-kHz. I use a simple symmetrical
device- 3 turns on a TV yoke ferrite core. Space from the antenna
to the ceil
is near 25 centimeters.
The antenna has
quite good directed properties at rotation within 30-90 degrees
the force of signals varied to 1-1,5
points on mine S-meter. I use a YAESU FT840 for my work in the
ether. Change of polarization (at rotation of the antenna on the
vertical side) appreciable changes has not given as well as change
of feeding points has not given large change in the force of signals.
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Helical Loop Antenna

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